Multiple switch-board



(No Model.) 8

M. G. KELLOGG.

MULTIPLE SWITCH BOARD.

o. 393,209, Patented Nov. 27, 1888.

'N-Tnn STATES PATENT OFFICE. 1

MILO G. KELLOGG, OF CHICAGO, ILLINOIS.

MULTIPLE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 393,509, dated November 27, 1888. Application filed January 28. 1888. Serial No. 262,215. (No model.)

To all whom it may concern.-

Be it known that I, MILO G. KELLOGG, of Chicago, Illinois, have invented certain new and useful Improvements in Multiple Switch- Boards for Telephone- Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone-exchange systems in which part of the subscribers lines are single-circuit lines and part of them are metallic-circuit lines; and it consists of apparatus for and a system of switching together the various lines of the exchange in the operation of the exchange system and a system of testing at one board of the exchange to determine whether a line is in use at another board.

In the drawings illustrating my invention, Figures 1 and l represent sections of two multiple switch -boards of the exchange to which the same lines are connected. Fig. 2 shows a complete diagram of the boards with all the cental o'flice apparatus, circuits, and connections necessary to illustrate my invention. Fig. 3 shows in diagram a subscribers station apparatus adapted for use on metalliccircuit lines of the system.

In Fig. 2, A is a sectional view ofthe switchboard shown in Fig. 1, and A is a sectional view of the switch-board shown in Fig. 1", each as indicated by the lines (I e. I place as many boards in the central office as are found necessary or desirable in order to properly answer the calls and make the necessary con nections. On each board is a spring-jack or other suitable switch for each line. Each springjack switch has a contact-spring which normally bears on an insulated contact-point and has a contact'piec-e insulated from the rest of the switch, (except by the line-connections, as indicated,) and is adapted to receive a loopswitch plug, and when the plug is inserted to disconnect the spring from the contact-point (on which it normally bears) and connect the two contactpieces of the plug with the spring and said insulated contact piece, respectively. In the figures, 99 represent the springs of the different switches, h It the contact-points on which the springs normally bear, and j j the insulated contact'pieces of the switches. Z Z are the switch-holes. a a are the rubber strips on which the spring-jack parts are mounted, as shown, and through the fronts of which are the switch-holes Z I, These holes are adapted to receive the s witch-plugs,'(marked D D, and when a plug is inserted into a switch it operates the switch, as above described.

The insulated contactpieces j j of the switches should be so placed that a test-plug or other switch-testing device may be readily applied to them. For the spring-jack switches which are to be used for single-circuit lines I provide still another contact-piece from those mentioned above, which is normally (or when a plug is not in a switch) disconnected from the line contact-points; but when the plug is inserted it is in contact with the spring-lever of the switch. I have shown this contactpiece as a spring also, and it is marked 9. When the plug is inserted in a switch, it raises the spring-lever g of the switch, so that it comes in contact with the spring 9. The switches for the single-circuit lines are marked 8, and those for the metallic-circuit lines are marked 8.

I use a loopswitch plug with a double flexible cord for each line on the board when its calls are to be answered. These plugs are marked D D, the construction of the plugs being the same whether they are for singlecircuit or metallic-circuit lines, but the connections to the plugs being different for the different kinds of lines. The plug D is for a singlecircuit line, and D is for a metallic-circuit line.

For eachloop switch plug at the board where it is located I provide a switching devieeadapted to receive the plug, and into which the plug is normally placed, and which normally connects one of the contact-pieces of the plug with the ground wire or connection of the lines, as shown, and as will hereinafter be described.

ar are the switching devices for the two lines shown, one device on each board.

Z l are the holes in which the plugs are normally placed, and g g are the contact-springs of the devices, with which one of the contactpieces of the plug connects when a plug is inserted.

m m are the two insulated contact-pieces of a plug, and n is the rubber insulation of the lug.

All the springsg" g of theseveral switching devices connect, as shown, to a common ground wire. or connection, in which is a constantlyacting rheotome, (marked It.) For each line is a looping-in switch (marked Y) connected to the line-circuit, as shown, and by which the operator attending the line may at will loop either her telephone or calling-gcnerator in its circuit. The looping-in switch of a line is located at the board where the loop-plug of the line is located and where the calls of the line are to be attended to. It should be conveniently mounted and placed, so that the opera tor can readily make the connections.

In the subscribers station apparatus for metalliccireuit lines (shown in Fig. 3) 1 is the telephone-switch. 2 is thecalling-generator. 3 is the signal-receiving bell, and 4. is the subscribers telephone. G in each case in the drawings is the groimd-conncetion. These parts may be the usual form of apparatus, and are connected as shown, or in other known ways. The callinggenerator is, however, modified, as will be described.

The generator has an automatic device(shown in the drawings) by which, when the crank is not in motion, the wire of the armature is shunted and the line is disconnected from the ground at the subscribers station, and when the generator is turned or operated the shunt is automatically removed and the line is connccted to the ground. The automatic device shown is a modification of a form very generally used, the modification being substantially in the arrangement of the contactpoints. It contains a V-shaped attachment to the hub of the driving-wheel, a pin in the shaft which engages the V -shaped arrangement, and a spring which presses against the wheel and brings the pin normally in the center of the V arrangement. The contactpoints are substantially as shown, and will produce the switching operations described above.

to and x are callingannunciators, one for each line shown, and each located in the circuit of the line at the board where its calls are to be answered. Two lines are shown, one a metallic-circuit line and marked line No. 1, and the other a single-circuit line and marked line No. 2. The two sides or branches of the metallieeireuit line are marked wire a and wire 1).

The circuit of the single-circuit line is as follows: from the subscribers ground through his station apparatus, (which may be the usual style for subscribers lines,)through the pairs of contact-points g h, successively, of its switches on the several hoards, going in each case to the point first, thence through its lineannunciator to one of the conductors of its double cord,and thence to the contaetpiece m of its double plug, and, when the plug is inserted into its switching device, to the ground through the contact-spring g and the rheotome It. Theother contact-piece, m, of the plug of a single-circuit line should be connected through the other conductor of its cord to the ground or to the common ground-wire, but the rheotome B should not be in its ground-circuit. All the contact-pieces jj, of a single-circuit line should be connected together and to their line between its switches and the subscribers station. All the contact-springs ofthe switches of the single-circuit lines should be connected to the ground, but the rheotome shouldnot be in their ground circuit. The drawings show the connections of a single-circuit line and its switch parts and apparatus as above described.

The circuit of a metallic-circuit line is as follows: One side or branch of a line-say wire ais connected with all the contact-pieeesj j ofits switches on the several boards,and also to the contact-pieces m of its loop-plug through one of the conductors of the double cord. The other side or branch of the line passes successively through the pairs of contact-pieces g h of its switches on the several boards, going in each case to the spring first, thence through its annunciator to the other conductor of the cord and to the contact-piece m of its double plug, and, when the plug is inserted into its switching device, through the contact spring 9" and the rheotome R to the ground. The two sides of the line unite at the subscribers station, and his apparatus is so connected into the circuit that when the generator is operated the ground thereby established is between the wire of the armature and the contactpiecesjj of the line-switches. In each case in switching, when a plug is taken from its normal position and placed in aline-switch, it is so placedin the switch that the contactpiece of the plug marked m makes connection with the springlever of the switch. To insure this the piece m may be conveniently marked.

The switching between the various lines of the exchange is as follows: When an operator receives a call from a metallic-circuit line assigned to her board to be answered, she finds out by testing,as will hereinafter be described, whether the line called for is in use. If it is not in use, she takes the plug of the line calling from its normal position and places it, as indicated, in the switch at her board of the line wanted. By so doing she removes the groundconnection through her rheotome from both the lines. If the line wanted is also a metallic-circuit line, the two lines are connected together in metallic circuit, and the annunciator and looping-in switch of the line calling only is in that circuit. If the line wanted is a singlecircuitline, they are connected in one circuit, and the annunciator and switch of the line calling only is in that circuit. Their combined circuit would then be from the ground of the single-circuit line of the subscribers station through the line to the piece of the loop-plug which is in connection with the contact-piece of the switch used, and thence through the metallic-circuit line to the other contactpiece of plug and the spring-lever g of the switch used to the lever g and to the ground. When an operator receives a call on a single-circuit line IIO assigned to her board to be answered,she finds out by testing whether the line called for is in use at another board. If it is not in use, she takes the plug of the line calling from its norrnal position and places it, as indicated, in the switch at her board of the line wanted. By so doing she removes the ground connection through the rheotome of both lines. The annunciator and looping-in switch of the line which called only is in the combined circuit thus established. It the line wanted is a metallic-circuitlinc,tl1e combined circuit is thus: from the ground through the flexible cord to the contact-piece of the plug connected with it, thence through the metallic'circuit line to the other contactpiece of the plug, and thence through the single-circuit line to the ground at the subscribers station. It the line wanted is a single-circuit line, the connection or circuit is thus: from the ground of the line calling to the contact-piece of the plug connected therewith, and thence through the contactpiecej of the switch of theline wanted,throngh the line, to the ground at the subscribersslation. The other contact-piece of the plug is then connected with the spring-lever of the switch and both are grounded; but the operation of the system is not affected thereby.

For each operator at her board I provide a test-receiving instrument grounded at one side or connected to the groundconneetion, (but the ground-circuit ol' the instrument must not be through the rheotome,) said instrument being connected on its other side to a testplng with a flexible cord or other suitable test arrangement, by which the operator may at will connect her test-receiving instrument on that side to any of the contact pieces j j at her board. In the test-circuits thus established should be a test battery or batteries. The testreceiving instruments are marked S, the testplugs are marked T, and the test batteries are marked 15'.

I will now describe the general principles of my test system.

It will be seen that the common wire or connection in which is the rheotome is permanently connected on one side of the rheotome to one side of each of the testrecciving instruments, such connection in the drawings being through the ground, and that said wire is normally connected on the other side of the rheotonieto each lincoftheexchange, (whether it be a metallic or single-circuit line,) but that when a line is switched for conversation such normal connection between it and the rheotome is broken. The other side of each testrecciving instrument is normally open and connected with a testplug adapted to be connected for testing with any line, whether the line be switched or not. When a line is tested by applying a tcstplug to it, as indicated above,(\vhetber it be a metallic or single circuit line,) and it is not switched, there will necessarily be a complete circuit established, in which is the test-receiving instrument, the battery, and the rheotome, and the test-receiving instrument, actuated by the battery, will respond to the make and breaks of the rheotome. When the line tested is switched, it is disconnected from the side of the rheotome with which it is normally connected, and there being no such complete circuit the instrument will not respond.

The test is applied for any line to determine whether or not it is in use by connecting the test-plug to the contact-piecej of the line at her board. The test-circuit of a metallic-circuit line, when not in use, is from the ground through the testreceiving instrument and battery, through the circuit of the line, the pairs of contact-points of its switches, its flexible cord and plug connected to that side of the line, the spring of the switching device of the line,and to ground through the rheotome. If the line is switched, either by its plug being withdrawn from its normal position or by a plugbeinginsertedintoanyofitslineswitches, this testcireuit is interrupted. The operator will know whether the line is in use or not as she does not or does hear the makes and breaks of the rheotome on her test-receiving instrument. The test-circuit of a single-circuit line when not in use is from the ground through the test-receiving instrument and battery to the contact-piece j of the line tested, thence through the pairs of contact points of its switches, its flexible cord and plug connected to the line, the spring of the switching-device otthe line, and to ground through the rheotome. If the line is switched either by its plug being withdrawn from its normal posi tion or by a plug beinginsertcd into any ofits lineswitches, this test'circuit is interrupted. The operator will therefore know in like man nor as with the metallic-circuit lines whether or not a line is in use.

The rhcotome shown (marked R) is a usual form of mechanical rhcotomc containing a clock-work movement actuated by a spring. Itcontains an oscillating bar fixed to the vergeshaft and standing at right angles to it. A pair of contact-points is connected with the bar or with the shaft in such a way that their connection is alternately made and broken with the oscillations. On the bar is a sliding weight, by which the rapidity of the oscillations may be regulated. The pair of contactpoints is properlyinsulated, and is connected into the circuit as indicated for the rheotome. Instead of the rheotome shown, any usual form of mechanical or electric rheotonie may be used.

The test-receiving instruments employed should be such as will be actuated by the batteries used and respond to the makes and breaks of the rheotome employed when connected in the test circuit described. The test battries should preferably be in the normallyopen portion of the test-circuit, as shown, as they will thus be consumed only during such portion of time as the test is being applied. It is evident that when the test is applied to a single-circuit line grounded at its outer end by the regularity of the sounds in her instrument if the line is not in use. The test-receiving instrument should be such as will respond to the make and break of the rheotome when thus connected to a single-circuit line.

It will be seen from the description of the system as above described that the operators can make all the necessary connections and testing for a telephone system with combined.

single and metallic circuit lines, and that the operations they go through with for each con nection are the same whether the lines switched be single or metallic circuit. The confusion which would result from having the two systems of testing and switching for the two kinds of lines is avoided. This result is obtained by the combination of apparatus I have shown and described.

I claim as my invention and desire to secure by Letters Patent 1. In atelephoneexchangesystem, metalliccircuit lines centering atatelephone exchange, one side or branch of each line being normally connected to a common ground wire or con? nection' at the central office, the other branch or side being normallyopen at the central office and the line being normally disconnected from the ground at the subscribers station, and a constantly-acting rheotome in said common ground wire or connection, in combination with switching devices to disconnect either of said lines from said common ground wire or connection when it is switched with another line for conversation, a test-receiving instrument at the central ofiice in a normally-open test-wiregrounded at one end,bntnotgrounded through the rheotome, a battery in said normally-open test-wire, and a switch-testing device to connect the normally open end of said test-wire to the normally-open end of any of said lines, substantially as set forth.

2. In a telephone exchange system, multiple switch-boards, metallic-circuit lines connected to said boards, one side or branch of each line being connected to a common ground wire or connection at the central office, the other side or branch being normally open at the central office at each board, the line being normally disconnected from the ground 'at the subscribers station, and a constantly-acting rheotome in said common ground wire or connection, in

combination with switching devices at each board to disconnect either of said lines from the common ground wire or connection when it is switched with another line for conversation, test-receiving instruments-one at each board-mach instrument being in a normallyopen test-wire grounded at one end, but not grounded through the rheotome, a switch'testing device to connect the normally-open end of said test-wire With the normally-open end of either of said lines, and a battery in the circuit between said switch-testing device and the rheotome, substantially as set forth.

3. In a telephone-exchange system, a testcircuit for a metallic-circuit line, consisting of the circuit of the line, a ground wire or connection at the central oflice, to which one of the branches of the line is normally connected, and a normally-open test-wire grounded on one side and connected on its other side to a switch-testing device adapted to be brought into contact with the other side or branch of the line, in combination with a switching device to disconnectsaid line from said ground wire or connection when it is switched with another line for conversatiomand a constantlyacting rheotome, a battery, and a test-receiving instrument in said test-circuit, substantially as set forth.

4. In a telephone-exchange system, a test circuit for a metallic-circuit line, consisting of the circuit of the line and a local test-circuit at the central office, one side of which is connected to one side or branch of the metallic-circuit line and the other side of which is connected with the switch-testing device to bring said side, at the will of the operator, into connection with the other side or branch of the line, in combination with a switching device to break said normal connection between the line and the local test-circuit when the line is switched for conversation, and a rheotome, a

battery, an d a test-receivi ng instrument in said test-circuit, substantially as set forth.

5. In a telephone-exchange system, two or more metallic-circuit lines and a local test-circuit at the central office, one side ofwhich is connected normally to one side or branch of each of the metallic-circuit lines and the other side i of which is connected to a switch-testing device to bring said side, at the will of the operator, into connection with the other side or branch of each of said lines in combination 7 with a switching device for each line to break said normal connection between the line and the local test-circuit when the line is switched for conversation, and a rheotome, a battery, and a test-receiving instrument in said local test-circuit, substantially as set forth.

6. In atelephone-exchange system, multiple switch-boards, metallic-circuit lines connected to said boards, a common wire or connection at the central office, one side of which is normally connected to one side or branch of each of the metallic-circuit lines, and switching devices at each board to disconnect any line from said common wire or connection when it is switched with another line for conversation, in combination with testreceiving instrumentsone at each board--each instrument being in an individual test-wire connected on one side with said common wire or connection and on its other side with a switch-testing de-- 1 V i r vice to connect it at the willof the operator with the other side or branch of each of the lines, and a rheotome and battery in the circuit comprising said common wire or connection and said individual test-wire.

7. In a telephone-exchange system, multiple switchboards, a metallic-circuit line normally disconnected from the ground at the subscribers station, a switch on each board for each line, each switch containing a pair of con tact points or pieces normally in contact, and a third contact-piecenormallyinsulatedfrom the rest of the apparatus, (except by the line-eonnections,)one ofthe sides or branches oftheline passing successively through the pairs of contact-points of its switches on the different boards, and thence to a ground wire or con nection, the other side or branch of the line being connected to said normally-insulated contact pieces of its switches on the different boards, a rheotome in said ground wire or connection, and a loop-switch-plug adapted to be inserted into a switch of the line, and when inserted to disconnect the pair of contact-points which are normally in contact and connect the two sides or branches of the line with the two contactpieces of the plug, respectively, in combination with test receiving instruments one at each boardeach instrument being grounded on one side and connected on its other side to a test-plug or other test device adapted to be brought into connection with said normally-insulated contact-piece at its board, and a battery in the test-circuit thus established, substantially as set forth.

8. In a telephone-exchange system, a switchboard, a telephone-line, aswiteh on said board for the line containing a pair of contact-points normally in contact, and a third contact normally insulated from the rest, (except by the line-connections,) the switch being adapted to receive a switch-plug, and when the plug is inserted to disconnect the contact-points which are normally in contact and to connect one of them with said third contact-piece, said third contact-piece being connected to the ground, (but not through a rheotome,) said contact point or piece which is connected to it when the switch-plug is inserted being connected to the ground through a rheotome and the other contact-piece connected to the line, substantially as set forth.

9. In a telephone exchange system, singlecircuit lines centering at a telephone ex; change, said lines being connected normally to a common ground wire or connection at the central office, and a rheotome in said common ground wire or connection, in combination with switching devices to disconnect either of said lines from said common ground wire or connection when it is switched with another line for conversation, a test-receiving instrument in the central office in a normally-open test-wire grounded at one end, but notgrounded through the rheotome, a battery in said normally'open testwirc, and a switch-testing device to connect the normally-open end of said test-wire to the line whether it is switched or not, substantially as set forth.

10. In a telephone-exchange system, multiple switch boards, single circuit lines connected to said boards and normally connected to a common ground wire or connection at the central oifice, and a rheotome in said common wire or connection, in combination with switching devices at each board to disconnect either of said lines from the common ground wire or connection when it is switched with anotherline for conversation,testreceiving instruments-one at each boardeach instrument being in a normallyopen test-wire grounded at one end, butnot grounded through the rheotome, a switch-testing device to connect the normally-open end of said test-wire to the line whether switched or not, and a battery in the test-circuit thus established, substantially as set forth.

11. In a telephone-exchange system, two or more single-circuit lines centering at a telephone-exchange, a rheotome at the central office, said lines being normally connected to one side of the rheotome, a test-receiving instrument connected on one side to the other side of the rheotome and on its other side to a switch-testing device adapted to be brought into connection with any of said lines whether it is switched or not, and a battery in the test circuit thus established, in combination with switching devices to disconnect either of said lines from said rheotome when it is switched with another line for conversation, substantially as set forth.

12. In atelephone-exchange system,aspringjack switch containing a contact-piece connected to the line, a contact-spring normally in connection with said contact-piece and grounded through a rheotome, and another contact piece normally insulated from the rest (except by the circuit-eonnections) and grounded, but not through the rheotome, in combination with a double or loop plug adapted to be inserted into the switch, and when inserted to disconnect the spring from the contactpiece with which it is normally in contact and connect it with the other contactpiece, and at the same time connect the two contactpieces of the plug with the first-mentioned contact-piece and the spring, respectively, substantially as set forth.

13. In a telephone-exchange system, multiple switch-boards, telephone'lines connected to each of said boards, a rhcotome at the central office, said lines being each normally connected to one side of said rheotome, test-recei ving instruments-one at each board-each test-receiving instrument being connected on one side to the other side of said rheotome and on its other side to a switch-testing plug or device adapted at the will of the operator to be brought into connection with any line at its board, and a battery in the test-circuit thus established, in combination with switching de vices to disconnect said normal connection of any line with the rhcotome when the line is IIO switched with another line for conversation,

substantially as set forth.

14. In a telephone-exchange system, a loopswiteh plug the two insulated contact-pieces of which are connected to the two sides or branches, respectively, of a metallic circuit line, in combination with a spring-jack switch for a single or ground circuit line, said switch having two eontact-pieces normally in connection and a third contact-piece normally insulatcd from .the rest, (except by the circuitconnections) one of said contact-pieces which are normally in connection being connected wii 1] the line and the other with aground wire or connection, and a rheotome in said ground wire or connection said third contact-piece being also connected to the ground, but not through the rheotome, said plug being adapted to be inserted into said switch, and when inserted to disconnect the two contactpieees of the switch which are normally in contact and connect them, respectively, with the two contact-pieces of the plug, and at the same time connect said third contact-piece to the contact-piece which is connected to the ground through the rheotome, whereby by the insertion of the plug into the switch the two lines are looped together into one circuit for conversatiomthe oiiice ground and the subscribers ground of the single-circuit line forming the two terminals of the circuit, and the rheotome is switched or shortcircuited from the circuit, substantially as set forth.

15. In a telephone-exchange system, multiple switch-boards, single and metallic circuit lines connected to said boards, a common groundconnection for said lines at the central oflice, in which is a rheotome, one branch of each of said metalliecircuit lines and said single-circuit lines being normally connected to said groulid-connection, the other branch of each of said metallic-circuit lines being normally open at each of the switch-boards and said metallic-circuit lines being normally ungronnded at the subscribers stations, and switching devices at each of the boards for each of the lines to disconnect the line from said ground-conncction when it is switched with another line for conversation, in combination with test-receiving instruments-one at each boardeach instrument being grounded 'on one side, but not through the rheotome, and

connected on its other side to a switch-testing plug or device, adapted at the will of the operator to connect the instrument to any single circuit line and 'to the normally-open end of any metallic-circuit line at her board, and a battery in the test-circuit thereby established, substantially as set forth.

16. In a tclephoneexchange system, the combination of multiple switch-boards, the subscribers lines grounded at their outer ends, the switches-one for each line on each board-the circuit-connections of the lines through their switches and to a common ground wire or connection, a rheotome in said common ground wire or connection, the testbolts-one for each switchconnccted to the lines between the subscribers stations and the switches, the tcst-circuitsone for each board-groundcd at one end and normally open to the lines at their other ends, a battery and a signal-receiving device in each test-cireuit, and a testplug adapted to close the testcircuit at the test-bolt of any line, said instrument being constructed to respond to the pulsations of current which pass through it when its tcst-circuit is closed to a line and the line is not disconnected at one of its switches from said ground wire or connection in which is the rheotome, substantially as set forth.

17. In a telephone-exchange system, the combination of multiple switch-boards, the subscribers lines, the switches -one for each line in each boardthe circuit-connections of the lines through their switches and to a common ground wire or connection, a rheotome in said common ground wire or connection, the test-bolts-one for each switehconnected to the lines between the subscribers stations and the switches, the testcircuitsonefor each board-grounded at one end and normally open to the lines at their other ends, a battery and a signal-receiving device in each test-circuit, and a test-plug adapted to close the test-circuit at the test-bolt of any line, substantially as set forth.

MILO G. KELLOGG'.

\Vitnesses:

Mrn'roN HEAD,

.JALVIN DEWoLF. 

